One of the process steps utilized in the fabrication of integrated circuits is plasma etching. In plasma etching, a patterned mask is formed over a layer (on a semiconductor substrate) that is to be etched and exposed to etch species in generated in a plasma etch tool which removes the layer where it is not protected by the patterned mask. Control of the dimension of the structures so etched is critical to the proper performance of the integrated circuit and is effected by the amount of etch by-product polymer coating the chamber and fixtures within the chamber of the plasma etch tool. However, etched dimension control deteriorates as more and more substrates are etched in the tool and the chamber becomes coated with excessive amounts of polymer. Thus, plasma etch tools must be periodically cleaned to remove the excessive amounts of polymer and seasoned to restore a minimum amount of polymer required to for etch dimension control. However, cleaning and seasoning themselves can effect line dimension control as well.
Therefore, there is a need for method and system for etched line-dimension control in a plasma etch tool that takes into account chamber cleaning and seasoning effects.